THE ROLE OF Δ(1232) IN TWO-PION EXCHANGE THREE-NUCLEON POTENTIAL

Abstract

In this paper we have studied the two-pion exchange three-nucleon potential (2πE-3NP) using an approximate SU(2)×SU(2) chiral symmetry of the strong interaction. The off-shell pion-nucleon scattering amplitudes obtained from the Weinberg Lagrangian are supplemented with contributions from the well-known σ-term and the Δ(1232) exchange. It is the role of the Δ-resonance in 2πE-3NP, which we have investigated in detail in the framework of the Lagrangian field theory. The Δ-contribution is quite appreciable and, more significantly, it is dependent on a parameter Z which is arbitrary but has the empirical bounds |Z|≤1/2. We find that the Δ-contribution to the important parameters of the 2πE-3NP depends on the choice of a value for Z, although the correction to the binding energy of triton is not expected to be very sensitive to the variation of Z within its bounds.